Communication method and apparatus

Abstract

The present application relates to the technical field of communications, and provides a communication method and apparatus. A transmitter acquires an orthogonal frequency division multiplexing (OFDM) signal, wherein the OFDM signal is obtained by preprocessing a symbol sequence, the preprocessing comprises frequency domain spectrum shaping (FDSS) and first processing, the first processing is to extend the symbol sequence to obtain an extended sequence, and the first processing is executed before the FDSS; the transmitter outputs the OFDM signal; and a receiver receives the OFDM signal, and demodulates the OFDM signal to obtain the symbol sequence. In the present application, after the symbol sequence has undergone the first processing, the length of the sequence is increased, so as to obtain an extended sequence; and the extended sequence is processed via the FDSS and is then sequentially processed via subcarrier mapping, inverse Fourier transform, etc., so as to obtain an OFDM signal. On the basis of the OFDM signal, in an ISAC scenario, the detection performance of a sensed target can be improved, and the demodulation performance of a communication signal can be ensured.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on February 4, 2024, with application number 202410161416.5 and application name "A Communication Method and Device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present application relate to the field of communication technology, and in particular to a communication method and apparatus. Background Art

[0004] Wireless sensing technology analyzes changes in wireless signals during propagation to determine the characteristics of the signal propagation space (channel), enabling scene perception. Integrated sensing and communications (ISAC) combines communication and perception, enabling future communication systems to incorporate both capabilities. When transmitting information over wireless channels, ISAC analyzes channel characteristics and perceives the physical characteristics of the surrounding environment, thereby enhancing both communication and perception capabilities.

[0005] The ISAC transmitter transmits a signal toward the target to be detected. After reflection from the target, the signal is received by the ISAC receiver. The ISAC receiver performs time-domain or frequency-domain digital signal processing on the echo and transmitted signals to generate a range profile. The ISAC then searches for peaks in the range profile to estimate the time delay. Finally, the distance to the detected target is determined based on the estimated time delay.

[0006] Frequency domain spectrum shaping (FDSS) can improve target detection performance (especially for weak targets, such as those with weak echo signal power). However, the introduction of FDSS degrades the communication demodulation performance of the ISAC. Summary of the Invention

[0007] The present application provides a communication method and apparatus for improving the communication demodulation performance of an ISAC while achieving target detection performance.

[0008] In a first aspect, the present application provides a communication method that can be performed by a transmitter. Unless otherwise specified, in the present application, the transmitter can be the transmitter itself (e.g., a network device, a terminal device), a component in the transmitter (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the transmitter's functions. This application does not specifically limit this.

[0009] The method can be applied to the 5th generation (5G) communication system or a communication system above 5G, and can also be applied to non-terrestrial communication systems, which is not specifically limited in this application. The method is performed as follows:

[0010] An orthogonal frequency division multiplexing (OFDM) signal is obtained, where the OFDM signal is obtained by preprocessing a symbol sequence, the preprocessing including: FDSS and a first process, where the first process extends the symbol sequence to obtain an extended sequence, the first process being performed before the FDSS; and the OFDM signal is output.

[0011] OFDM is one of the waveforms currently used by 4G and 5G systems. To ensure uplink coverage, the uplink transmission of 4G and 5G systems currently also supports discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT spreading OFDM, DFT-s-OFDM), which has the characteristics of a single-carrier waveform and a peak-to-average power ratio (PAPR) that is much lower than multi-carrier waveforms such as OFDM. However, in the ISAC scenario, some studies recommend the use of single-carrier or waveforms with single-carrier properties (such as DFT-s-OFDM) for perception, but due to the imbalance of frequency domain signals, the perception performance is impaired. In contrast, multi-carrier OFDM waveforms can achieve frequency domain signal balance, such as subcarriers carrying phase-shift keying symbols.

[0012] In this application, an OFDM signal is obtained by subjecting a symbol sequence to a first processing step and processing such as FDSS. The first processing results in an extended sequence whose length is greater than the symbol sequence. Therefore, redundancy is introduced into the symbol sequence after the first processing. After the FDSS processing, the extended sequence is then subjected to subcarrier mapping and inverse Fourier transform, resulting in an OFDM signal. Based on this OFDM signal, FDSS can improve target detection performance in ISAC scenarios, while the first processing can mitigate the performance loss in OFDM signal communication demodulation caused by FDSS.

[0013] In an optional manner, the pre-processing further includes: performing a cyclic shift on the symbol sequence, and the cyclic shift is performed before the first processing.

[0014] In this application, appropriate cyclic shift helps to improve the demodulation performance of OFDM signals.

[0015] In an optional manner, the first processing extends the symbol sequence to obtain an extended sequence, including: extending the symbol sequence with a length of M based on an extended length L to obtain an extended sequence with a length of (M+L), where M and L are both positive integers, and L does not exceed M.

[0016] In an optional manner, L is determined based on at least one of the following:

[0017] The modulation and coding scheme (MCS) M, or the first factor θ corresponding to the OFDM signal; wherein the value of the first factor is related to the window function of the FDSS.

[0018] By determining L based on the above parameters, it is possible to balance the degree of redundancy introduced into the symbol sequence and the degree of improvement in the encoding and decoding bit rate, thereby improving the demodulation performance of OFDM signal communication.

[0019] In an optional manner, the first processing extends the symbol sequence to obtain an extended sequence, comprising: extending the symbol sequence with a length of M based on an extension factor α to obtain an extended sequence with a length of (M+L);

[0020] In an optional manner, α is determined based on at least one of the following:

[0021] The MCS corresponding to the OFDM signal, or the first factor θ; wherein the value of the first factor is related to the window function of the FDSS.

[0022] By determining α based on the above parameters, the degree of redundancy introduced into the symbol sequence and the degree of improvement in the encoding and decoding rate can be balanced, thereby improving the demodulation performance of OFDM signal communication.

[0023] In an optional manner, the extended sequence includes a first extended sequence with a length of L1, a second extended sequence with a length of L2, and the symbol sequence with a length of M; wherein L1+L2=L; wherein the first extended sequence is obtained by performing sequence processing on the first sequence in the symbol sequence, and the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; and the second extended sequence is obtained by performing sequence processing on the second sequence in the symbol sequence, and the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence.

[0024] In the present application, the first extended sequence and the second extended sequence can be considered as a redundancy added to the symbol sequence. By introducing redundancy, the loss of OFDM signal communication demodulation performance caused by FDSS can be reduced / mitigated.

[0025] In an optional embodiment, L1 is equal to L2.

[0026] Based on the above L1 equals L2 design, when L is given, the frequency selectivity gain of the OFDM signal on the multipath channel can be maximized.

[0027] In an optional manner, the sequence processing of the first processing includes one of the following:

[0028] Obtaining a first extended sequence and a second extended sequence based on sequence replication, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the head of the symbol sequence; or,

[0029] Taking conjugation of the sequence to obtain a first extended sequence and a second extended sequence, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the beginning of the symbol sequence; or,

[0030] Obtaining a first extended sequence and a second extended sequence based on sequence reversal, adding the first extended sequence to the head of the symbol sequence, and adding the second extended sequence to the tail of the symbol sequence; or,

[0031] A first extended sequence and a second extended sequence are obtained based on sequence reversal and sequence conjugation, the first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence.

[0032] The shape of the FDSS window function resembles a mountain peak, i.e., the amplitude of the window function is high in the middle and low on both sides. In this application, by introducing a redundant design that matches the shape characteristics of the window function, i.e., adding a first extended sequence to the tail or head of the symbol sequence, and adding a second extended sequence to the head or tail of the symbol sequence, the degradation of the two subsequences in the symbol sequence (i.e., the subsequence corresponding to index 0 to index L1-1 and the subsequence corresponding to index M-L2 to index M-1) caused by FDSS processing can be reduced, thereby improving the demodulation performance of OFDM signal communication.

[0033] In an optional manner, the transmitter also obtains or outputs a first notification message, where the first notification message is used to indicate at least one of the following parameters: the shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length of the symbol sequence M, L, the relative relationship between L and M, or the expansion factor α.

[0034] Based on the first notification message, the transmitter may determine a shift amount of the cyclic shift, so as to perform a cyclic shift of the symbol sequence by the corresponding shift amount before the first processing.

[0035] Based on the first notification message, the transmitter can determine the length of the extended sequence, the length of the symbol sequence, the length of the first extended sequence and the length of the second extended sequence, which are used to determine the transport block size carried by the OFDM signal (that is, the number of bits carried by the OFDM signal) and for OFDM signal generation.

[0036] In addition, the transmitter outputs (can also be understood as sending) the first notification message, and the receiver receives the first notification message.

[0037] In an optional manner, the transmitter further obtains or outputs a second notification message, where the second notification message is used to indicate a sequence processing manner of the first processing.

[0038] Based on the second notification message, the transmitter may determine a sequence processing manner of the first processing and generate an OFDM signal based on the determination.

[0039] In addition, the transmitter outputs a second notification message, and the receiver receives the second notification message.

[0040] In a second aspect, the present application provides a communication method that can be executed by a receiver. Unless otherwise specified, in the present application, the receiver can be the receiver itself (e.g., a network device, a terminal device), a component in the receiver (e.g., a processor, a chip, or a chip system), or a logic module or software that implements all or part of the transmitter's functions. This application does not specifically limit this.

[0041] This method can be applied to 5G communication systems or communication systems above 5G, and can also be applied to non-terrestrial communication systems, which is not specifically limited in this application. Execution is as follows:

[0042] Receive an OFDM signal; demodulate the OFDM signal to obtain a symbol sequence, wherein the OFDM signal is obtained by preprocessing the symbol sequence, the preprocessing including: frequency domain spectrum shaping (FDSS) and a first processing, the first processing extending the symbol sequence to obtain an extended sequence, and the first processing is performed before the FDSS.

[0043] In an optional manner, the pre-processing further includes: performing a cyclic shift on the symbol sequence, and the cyclic shift is performed before the first processing.

[0044] In an optional manner, the first processing extends the symbol sequence to obtain an extended sequence, including: extending the symbol sequence with a length of M based on an extended length L to obtain an extended sequence with a length of (M+L), where M and L are both positive integers, and L does not exceed M.

[0045] In an optional manner, L is determined based on at least one of the following:

[0046] The modulation and coding scheme MCS, M, or the first factor θ corresponding to the OFDM signal; wherein the value of the first factor is related to the window function of the FDSS.

[0047] In an optional manner, the first processing extends the symbol sequence to obtain an extended sequence, comprising: extending the symbol sequence with a length of M based on an extension factor α to obtain an extended sequence with a length of (M+L);

[0048] In an optional manner, α is determined based on at least one of the following:

[0049] The modulation and coding scheme MCS corresponding to the OFDM signal, or the first factor θ; wherein the value of the first factor is related to the window function of the FDSS.

[0050] In an optional manner, the extended sequence includes a first extended sequence with a length of L1, a second extended sequence with a length of L2, and the symbol sequence with a length of M; wherein the first extended sequence is obtained by performing sequence processing on the first sequence in the symbol sequence, and the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; the second extended sequence is obtained by performing sequence processing on the second sequence in the symbol sequence, and the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence.

[0051] In an optional embodiment, L1 is equal to L2.

[0052] In an optional manner, the sequence processing of the first processing includes one of the following:

[0053] Obtaining a first extended sequence and a second extended sequence based on sequence replication, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the head of the symbol sequence; or,

[0054] Taking conjugation of the sequence to obtain a first extended sequence and a second extended sequence, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the beginning of the symbol sequence; or,

[0055] Obtaining a first extended sequence and a second extended sequence based on sequence reversal, adding the first extended sequence to the head of the symbol sequence, and adding the second extended sequence to the tail of the symbol sequence; or,

[0056] A first extended sequence and a second extended sequence are obtained based on sequence reversal and sequence conjugation, the first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence.

[0057] In an optional embodiment, the receiver also obtains or outputs a first notification message, where the first notification message is used to indicate at least one of the following parameters: the shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length of the symbol sequence M, L, the relative relationship between L and M, or the expansion factor α.

[0058] Based on the first notification message, the receiver can determine the length of the spreading sequence, the length of the symbol sequence, the length of the first spreading sequence, and the length of the second spreading sequence, and determine how to demodulate the OFDM signal.

[0059] Based on the first notification message, the receiver may determine a cyclic shift amount for performing a reverse cyclic shift operation corresponding to the transmitting end to restore the symbol sequence.

[0060] In addition, the receiver outputs (which may also be understood as sending) a first notification message.

[0061] In an optional manner, the receiver further obtains or outputs a second notification message, where the second notification message is used to indicate a sequence processing manner of the first processing.

[0062] Based on the second notification message, the receiver can determine the sequence processing method of the first processing to enable demodulation of the received OFDM signal. The receiver can perform different demodulation processing based on its own capabilities. For example, if the receiver capability is limited, the receiver can complete the recovery of the symbol sequence based only on the middle M data among the received (M+L) data. That is, the L1 data corresponding to the first extended sequence and the L2 data corresponding to the second extended sequence among the received (M+L) data are not used for the recovery of the symbol sequence. If the receiver capability is higher, the receiver can also use the L1 data corresponding to the first extended sequence and the L2 data corresponding to the second extended sequence among the received (M+L) data to obtain a more accurate estimate of the symbol sequence.

[0063] In addition, the receiver outputs (also understood as sending) a second notification message.

[0064] In a third aspect, an embodiment of the present application provides a communication device, which may be a terminal device or a network device (such as the transmitter in the first aspect or the receiver in the second aspect). The communication device has the functions of implementing the first or second aspect above. For example, the communication device includes modules, units, or means corresponding to the steps involved in the first or second aspect above. The functions, units, or means may be implemented through software or hardware, or may be implemented through hardware executing the corresponding software implementation.

[0065] In one possible design, the communication device includes a processing unit and a transceiver unit, wherein the transceiver unit can be used to send and receive signals to achieve communication between the communication device and other devices; the processing unit can be used to perform some internal operations of the communication device. The transceiver unit can be called an input / output unit, a communication unit, etc., and the transceiver unit can be a transceiver; the processing unit can be a processor. When the communication device is a module (such as a chip) in a communication device, the transceiver unit can be an input / output interface, an input / output circuit, or an input / output pin, etc., and can also be called an interface, a communication interface, or an interface circuit, etc.; the processing unit can be a processor, a processing circuit, or a logic circuit, etc.

[0066] In another possible design, the communication device includes a processor and may also include a transceiver, the transceiver is used to send and receive signals, and the processor executes program instructions to complete the method in any possible design or implementation of the first aspect or the second aspect above. The communication device may also include one or more memories, the memories are used to couple with the processor, and the memories can store the necessary computer programs or instructions for implementing the functions involved in the first aspect or the second aspect above. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first aspect or the second aspect above.

[0067] In another possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of the first or second aspect. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design or implementation of the first or second aspect.

[0068] In another possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first aspect or the second aspect above.

[0069] It can be understood that in the third aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory and the processor can be set separately. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0070] In a fourth aspect, an embodiment of the present application provides a communication system, which includes the above-mentioned transmitter and receiver.

[0071] In a fifth aspect, the present application provides a chip system, which includes a processor and may also include a memory, for implementing the method described in the first or second aspect. The chip system can be composed of a chip or include a chip and other discrete devices.

[0072] In a sixth aspect, the present application also provides a computer-readable storage medium, which can be a volatile storage medium or a non-volatile storage medium. The computer-readable storage medium stores computer-readable instructions. When the computer-readable instructions are run on a computer, the computer executes the method in the first aspect or the second aspect.

[0073] In a seventh aspect, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the methods of the embodiments of the first or second aspect above.

[0074] For the technical effects that can be achieved in the above-mentioned second to seventh aspects, please refer to the description of the technical effects that can be achieved by the corresponding possible design schemes in the above-mentioned first aspect, and this application will not repeat them here. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] FIG1 shows a schematic diagram of a communication system provided by an embodiment of the present application;

[0076] FIG2 shows a schematic diagram of an ISAC scenario provided by an embodiment of the present application;

[0077] FIG3 shows a schematic diagram of signal processing of an OFDM system;

[0078] FIG4 is a schematic diagram showing a frequency response corresponding to different roll-offs;

[0079] Figure 5 shows a schematic diagram of the changes in perception performance after the introduction of FDSS;

[0080] FIG6 shows a schematic diagram of the process of adding FDSS;

[0081] FIG7 shows a schematic diagram of the process of adding FDSS;

[0082] FIG8 is a schematic diagram showing the change of subcarrier energy;

[0083] FIG9 is a schematic diagram showing the BER of an OFDM signal;

[0084] FIG10 shows a schematic diagram of the process of bandwidth broadening;

[0085] FIG11 shows a schematic flow chart of a method for generating an OFDM signal;

[0086] FIG12 shows a schematic diagram of the filter's time domain response;

[0087] FIG13A shows a schematic diagram of a first process;

[0088] FIG13B shows a schematic diagram of a first process;

[0089] FIG13C shows a schematic diagram of a first process;

[0090] FIG13D shows a schematic diagram of a first process;

[0091] FIG14A shows a schematic diagram of a first process and FDSS;

[0092] FIG14B shows a schematic diagram of a first process and FDSS;

[0093] FIG15A shows a schematic diagram of a first process and FDSS;

[0094] FIG15B shows a schematic diagram of a first process and FDSS;

[0095] FIG16 shows a schematic diagram of a simulation result;

[0096] FIG17A shows a schematic diagram of a simulation result;

[0097] FIG17B shows a schematic diagram of a simulation result;

[0098] FIG17C shows a schematic diagram of a simulation result;

[0099] FIG17D shows a schematic diagram of a simulation result;

[0100] FIG18 shows a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0101] FIG19 shows a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0102] FIG20 shows a schematic structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0103] In order to make the purpose, technical solutions and advantages of this application clearer, the present application will be further described in detail below with reference to the accompanying drawings. The specific operating methods in the method embodiments can also be applied to the device embodiments or system embodiments. In the description of this application, unless otherwise specified, "multiple" means two or more. Therefore, the implementation of the device and method can refer to each other, and the repeated parts will not be repeated.

[0104] The technical solutions provided in the embodiments of the present application can be applied to 5G systems, or to future communication systems or other similar communication systems. In addition, the technical solutions provided in the embodiments of the present application can be applied to cellular links, public land mobile networks (PLMN), machine to machine (M2M) networks, Internet of Things (IoT) networks or other networks. It can also be applied to links between devices, such as device to device (D2D) links. D2D links can also be called sidelinks, where sidelinks can also be called side links or side links, etc. In the embodiments of the present application, the above terms all refer to links established between devices of the same type, and their meanings are the same. The so-called devices of the same type can be links between terminal devices, links between base stations, links between relay nodes, etc., and the embodiments of the present application do not limit this.

[0105] Figure 1 is a schematic diagram of a wireless communication system applicable to the present application. As shown in Figure 1 , the wireless communication system may include at least one network device, such as network device 111, network device 112, and network device 113. The wireless communication system may also include at least one terminal device, such as terminal device 121, terminal device 122, terminal device 123, terminal device 124, terminal device 125, terminal device 126, and terminal device 127. The communication method between network devices may be backhaul, such as the communication method between network device 111 and network device 112, or the communication method between network device 111 and network device 113. The communication method between network devices and terminal devices may be enhanced mobile broadband (eMBB), such as the communication method between network device 112 and terminal device 121. The communication method between network devices and terminal devices may be multi-site transmission, such as the communication method between network devices 112, network device 113, and terminal device 124. The communication method between terminal devices may be D2D. For example, the communication method between terminal device 122 and terminal device 125.

[0106] A terminal device may be a device capable of receiving scheduling and instruction information from network devices, providing voice and / or data connectivity to a user, or a handheld device with wireless connection capabilities, or other processing devices connected to a wireless modem. The terminal device may communicate with one or more core networks or the Internet via a radio access network (RAN). For example, the terminal device may be a portable, pocket-sized, handheld, computer-built-in, or vehicle-mounted mobile device. The terminal device may also be referred to as a subscriber unit (SU), subscriber station (SS), mobile station (MS), remote station (MS), access point (AP), remote terminal (AP), access terminal (AP), user agent (UA), customer premises equipment (CPE), terminal, user equipment (UE), mobile terminal (MT), etc. The terminal device may also be a wearable device. The terminal device may also be a device in a next-generation communication system. For example, terminal devices in 5G networks or terminal devices in future evolved PLMN networks, terminal devices in NR communication systems, etc.Currently, terminal devices may include: mobile phones, tablet computers, laptop computers, PDAs, customer-premises equipment (CPE), mobile internet devices (MIDs), wearable devices (such as smart watches, smart bracelets, and pedometers), in-vehicle equipment (such as cars, bicycles, electric vehicles, airplanes, ships, trains, and high-speed trains), virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, smart home devices (such as refrigerators, televisions, air conditioners, and electric meters), intelligent robots, workshop equipment, wireless terminals in self-driving vehicles, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, and flying devices (such as intelligent robots, hot air balloons, drones, and airplanes). The terminal device may also be other devices with terminal functions. For example, the terminal device may also be a device that serves as a terminal in D2D communication.

[0107] A network device is an entity on the network side that transmits or receives signals. For example, a transmission reception point (TRP) or a gNB. A network device can be an AP in a wireless local area network (WLAN), a base transceiver station (BTS) in a global system for mobile communication (GSM) or code division multiple access (CDMA), a base station (nodeB, NB) in wideband code division multiple access (WCDMA), or an evolved node B (eNB or eNodeB) in long-term evolution (LTE). A network device can also be a relay station or access point, or a network device in an in-vehicle device, wearable device, or 5G network, or a network device in a future evolved PLMN, or a device such as a gNodeB / gNB in ​​a NR system. In some deployments, a gNB can include a CU and a DU. The CU implements some of the gNB's functions, and the DU implements some of the gNB's functions. For example, the CU is responsible for processing non-real-time protocols and services. For example, it implements radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) layer functions. The DU is responsible for processing physical layer protocols and real-time services. For example, it implements functions of the radio link control (RLC), medium access control (MAC), and physical (PHY) layers. The gNB may also include an active antenna unit (AAU). The AAU implements some physical layer processing functions, RF processing, and active antenna-related functions. Because information implemented in the RRC layer ultimately becomes information in the PHY layer, or is converted from information in the PHY layer, in this architecture, higher-layer signaling (such as RRC layer signaling) can also be considered to be sent by the DU, or by both the DU and the AAU. It is understood that a network device can be a device that includes one or more of a CU node, a DU node, or an AAU node.In addition, the CU may be a network device in an access network (radio access network, RAN), and the CU may be a network device in a core network (core network, CN), which is not limited in this application. In addition, in an embodiment of the present application, the network device provides services for a cell, and the terminal device communicates with the network device through the transmission resources used by the cell (for example, frequency domain resources, or spectrum resources). The cell may be a cell corresponding to a network device (for example, a base station). The cell may belong to a macro base station or a base station corresponding to a small cell. For example, the small cell may include: a metro cell, a micro cell, a pico cell, a femto cell, etc. Since the small cell has the characteristics of small coverage and low transmission power, the small cell can provide high-speed data transmission services. In addition, in other possible cases, the network device may be other devices that provide wireless communication functions for the terminal device. The embodiments of the present application do not limit the specific technology and specific device form adopted by the network device. For example, in an open radio access network (ORAN) system, CU may also be referred to as O-CU (open CU), DU may also be referred to as O-DU, CU-CP may also be referred to as O-CU-CP, CU-UP may also be referred to as O-CU-UP, and RU may also be referred to as O-RU. For the convenience of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples for description. Any of the CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0108] To facilitate understanding of the embodiments of the present application, the following is a brief explanation of the terms involved in the embodiments of the present application.

[0109] 1) ISAC

[0110] ISAC integrates communication and perception, enabling future communication systems to simultaneously perform both functions. While transmitting information over wireless channels, ISAC proactively learns and analyzes channel characteristics to perceive the physical characteristics of the surrounding environment, thereby enhancing these two functions. Communication refers to the transmission of information between two or more communication devices. Perception refers to the detection of physical environment parameters based on communication signals, such as ranging and speed measurement. As shown in Figure 2, base station transmission signals can be used to perceive environmental information, assisting in the design of communication links to avoid obstacles (such as cars) and improve communication performance.

[0111] ISAC uses a signal that meets both communication and sensing requirements, such as an OFDM signal. The ISAC transmitter transmits an OFDM signal toward the target to be sensed. After the OFDM signal reflects off the target, it generates an echo signal, which is delayed compared to the transmitted signal. At the ISAC receiver, digital signal processing in the time or frequency domain is performed on the echo and transmitted signals to generate a range profile. The ISAC then searches for peaks in the range profile to estimate the time delay. Finally, the distance to the perceived target is determined based on the delay estimate.

[0112] OFDM is one of the waveforms currently used by 4G and 5G systems. In order to ensure uplink coverage, the uplink transmission of 4G and 5G systems currently also supports discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT spreading OFDM, DFT-s-OFDM), which has the characteristics of a single-carrier waveform, and the peak to average power ratio (PAPR) is much lower than multi-carrier waveforms such as OFDM. However, in the ISAC scenario, some studies recommend the use of single-carrier or waveforms with single-carrier properties (such as DFT-s-OFDM) for perception, but due to the imbalance of frequency domain signals, additional related designs are required. In contrast, frequency domain signal imbalance can be achieved based on multi-carrier OFDM waveforms, such as subcarriers carrying phase-shift keying symbols.

[0113] 2) OFDM signal

[0114] Figure 3 is a schematic diagram of signal processing in an OFDM system. The input signal at the transmitter is a frequency domain signal {S(p)}. The frequency domain signal is converted into an M-dimensional data block S(kM), S(kM+1), ..., S(kM+M-1) by a serial-to-parallel (S / P) module. k =[S(kM),S(kM+1),…,S(kM+M-1)] T , where the subscript k represents the OFDM symbol number and the superscript T represents the transposition. Through subcarrier mapping, S k The M data carried modulates N of the N subcarriers sc subcarriers, where N sc =M, the rest (NN sc ) subcarriers are modulated by data 0. N-dimensional data vector X k N complex time domain sampling points x are obtained by N-point inverse discrete Fourier transform (IDFT) k =[x k (0),x k (1),…,x k (N-1)]T .x k After the parallel-to-serial conversion module, the cyclic prefix (CP) operation is performed. By adding CP, the x k The last G samples of x are appended to the G samples. k The time domain OFDM signal is obtained at the beginning of the signal. After the digital-to-analog conversion, the OFDM signal is transmitted through the antenna of the signal transmitter. The OFDM signal is transmitted through the channel. The signal receiving end receives the OFDM signal, and after analog-to-digital conversion, CP removal, serial-to-parallel conversion module, N-point discrete Fourier transform (DFT), subcarrier demapping, and parallel-to-serial conversion module, the frequency domain signal {S(p)} is obtained. k (n), n=0,1,…,N-1 can be written as the following formula 1:

[0115] Among them, X k (n′), n′=0,1,…,N-1 represents the output of subcarrier mapping, e represents Euler constant, j represents imaginary unit, 2 =-1. The subcarrier mapping rule is shown in the following formula 2:

[0116] Where n0 is an integer, S k (l) is S k The lth element of sc -1.

[0117] It should be understood that when the number of transform points N satisfies certain constraints, such as when N is a power of 2, 3, or 5, the IDFT can also be implemented using the efficient inverse fast Fourier transform (IFFT). Correspondingly, the DFT can also be implemented using the efficient FFT. In the following text, IDFT and IFFT are interchangeable, while DFT and fast Fourier transform (FFT) are interchangeable.

[0118] N sc is the number of subcarriers corresponding to the OFDM signal transmission bandwidth. sc Equal to M. It should be understood that N sc It can also be greater than M. For example, in this application, the length of S k Do sequence expansion and assume that the length of the expanded sequence is equal to N sc Therefore, N sc ≥M.

[0119] 3) Roll-off and spectrum extension factor

[0120] Roll-off is the steepness of the frequency response function over frequency. Figure 4 shows the frequency responses for different roll-offs (β = 0, 0.25, 0.5, and 1). The frequency response with a rectangular shape (i.e., β = 0) is the steepest. In practical applications, filters with rectangular window frequency responses are difficult to implement. Using roll-off can reduce the difficulty of filter implementation but increase the bandwidth. The roll-off factor is defined as the following formula 3:

[0121] The no-roll-off bandwidth corresponds to the bandwidth when β = 0. In conjunction with Figure 4 , it can be seen that when β = 1, the bandwidth doubles, and when β = 0.5, the bandwidth increases by 50%.

[0122] In addition, regarding spectrum / bandwidth extension, there is also a spectrum / bandwidth extension factor defined as the following formula 4:

[0123] For example, if β=1, the spectrum / bandwidth expansion factor is 0.5; if β=0.5, the spectrum / bandwidth expansion factor is 1 / 3.

[0124] In this application, in the ISAC scenario, the use of FDSS can reduce the level of mid-range image side lobes and improve the target detection performance. The echo signal power generated by the pth (0≤p≤P-1) target is α p (α p >0), and the relative delay of the transmitted signal is τ p After frequency domain windowing, the range image |χ(τ)| is expressed as follows:

[0125] Where ω(l),l=0,1,…,N sc -1 represents the FDSS window function coefficient; ∝ represents the proportional symbol; and τ p , are all integers, and τ p , Does not exceed the CP length. Frequency domain signal After subcarrier demapping, we get

[0126] The following figure shows the change in the perceived performance brought about by FDSS. k(l) is a QPSK symbol. The sensed targets are denoted as Target 1 and Target 2. The echo signal power generated by Target 1 is 30 dB higher than the echo signal power generated by Target 2. The relative delay between the echo signal generated by Target 1 and the transmitted signal is 12 samples, i.e., τ0 = 12, while the relative delay between the echo signal generated by Target 2 and the transmitted signal is 75 samples, i.e., τ1 = 75.

[0127] Figure 5 shows the range images when only target 1 is present without FDSS; when both targets 1 and 2 are present without FDSS; when only target 1 is present with FDSS; and when both targets 1 and 2 are present with FDSS. As shown in Figure 5, when there is no FDSS, the main lobe of the range image produced by target 2 (located at τ = 75) is lower than the side lobe of the range image produced by target 1 (located at τ = 29). This causes the side lobe position of the range image produced by target 1 to be mistakenly identified as the position of target 2, resulting in an estimated τ of 29. When FDSS is present, the side lobe of the range image produced by target 1 is suppressed to a lower level, below the main lobe level of the range image produced by target 2. In this case, the range image produced when both targets 1 and 2 are present with FDSS contains two larger main lobes, with the main lobe peaks located at the positions of targets 1 and 2, respectively. Based on this, weak target 2 can be correctly estimated.

[0128] It should be noted that in the ISAC scenario, there are three ways to add FDSS:

[0129] Method 1: Add FDSS only at the transmitter end, as shown in Figure 6. The frequency domain signal {S(p)} is processed by the serial-to-parallel conversion module and then FDSS is performed. Then, subcarrier mapping, N-point IDFT, parallel-to-serial conversion module, CP addition, and digital-to-analog conversion are performed to obtain the OFDM signal. For adding FDSS only at the transmitter end, the frequency domain signal corresponding to the transmitted signal is S k (l)*ω T,only (l), where ω T,only (l) = ω(l), ω(l) can be understood by referring to the above formula 5. In the absence of noise, the frequency domain signal output by subcarrier mapping is shown in the following formula 6:

[0130] From this we can see that and (also S k The conjugate dot product of (l) can produce the formula 5

[0131] Method 2: Add FDSS only at the receiving end of the signal, as shown in Figure 7 below. The echo signal undergoes DFT, subcarrier demapping, FDSS, frequency domain dot multiplication, subcarrier mapping, and IDFT to obtain the range image. For adding FDSS only at the receiving end, the frequency domain signal corresponding to the transmitted signal is S k (l). For the echo signal (in the absence of noise, the subcarrier mapping output frequency domain signal is Adding FDSS can be expressed as the following formula 7:

[0132] Among them, ω R,only (l)=ω(l), ω(l) can be understood with reference to the above formula 5.

[0133] From this we can see that and The dot product can produce the formula 5

[0134] Method 3: Add FDSS on both the transmitting and receiving sides. Adding FDSS on both the transmitting and receiving sides results in the frequency domain signal corresponding to the transmitted signal being as shown in the following formula 8:

[0135] in, ω(l) is understood by referring to the above formula 5, where x makes the transmission signals of the three modes have the same power, that is, In the absence of noise, the subcarrier demapping module outputs a frequency domain signal as shown in the following formula 9:

[0136] After adding FDSS, we get the following formula 10:

[0137] in,

[0138] It should be noted that adding FDSS only to the receiving end or only to the transmitting end has the same perceived signal-to-noise ratio (i.e., the signal-to-noise ratio at the main lobe peak). Splitting FDSS into the transmitting and receiving sides has a higher perceived signal-to-noise ratio than adding FDSS only to the receiving end or only to the transmitting end. Assuming S k (The sequence obtained by the serial-to-parallel conversion module of the frequency domain signal) is a QPSK symbol sequence, and the perceived signal-to-noise ratio gain is 20*log10(x 2 )dB. Assume that ω(l) is a raised cosine (RC) with a roll-off factor of β, and is the root raised cosine (RRC) with a roll-off factor of β, N sc=720. Table 1 shows the corresponding x values ​​and the perceived signal-to-noise ratio gain under different β values. For example, β is 0.2, x is 1.0332, 20*log10(x 2 ) is 0.56dB. Based on Table 1, it can be seen that the perceived signal-to-noise ratio gain increases monotonically with the increase of β value.

[0139] Table 1

[0140] Using FDSS can improve perception performance, but it also impairs communication performance. Figure 8 shows the amplitude of data carried on subcarriers with and without FDSS at the transmitter. As shown in Figure 8, the use of FDSS increases the energy of the middle subcarriers and reduces the energy of the edge subcarriers, which degrades the demodulation performance of the data carried on the edge subcarriers, such as the bit error rate (BER). Figure 9 shows the BER of the demodulated OFDM signal in an additive white Gaussian noise (AWGN) channel with and without FDSS. As shown in Figure 9, the use of FDSS degrades the demodulation BER of the OFDM signal.

[0141] Using FDSS in OFDM signals can improve the detection performance of targets in ISAC (especially weak targets (i.e. targets with weak echo signal power)), but it will deteriorate the demodulation performance of OFDM signals. Based on this, in order to improve the communication demodulation performance in the ISAC scenario while ensuring the target detection performance, this application introduces a redundant sequence before FDSS processing to improve the demodulation performance of OFDM signals. As shown in Figure 10, the frequency domain signal S k The input of the bandwidth extension module (also called the sequence extension module, used to introduce redundant sequences) and the output of the bandwidth extension module This serves as the input to the FDSS module. The output of the FDSS module is equal to the input multiplied by the FDSS coefficients. Subcarrier mapping, IFFT, and CP addition are then performed to produce the OFDM signal. The bandwidth extension module's processing can be understood by referring to the first processing description below and will not be detailed here.

[0142] It should be understood that, although not shown in FIG. 10 , the frequency domain signal S k Before entering the bandwidth extension module, it can also be cyclically shifted by c0, where c0 is an integer. Elements are recorded as The symbol sequence of is cyclically shifted to point c0 to generate the symbol sequence d(m), d(m) and The relationship between them is shown in the following formula 11:

[0143] Here, mod represents the remainder operation. For example, 12 mod 5 = 2.

[0144] 11 , an OFDM signal generation method is provided, which can be executed through interaction between a transmitter and a receiver. Wherein, unless otherwise specified, in this application, the transmitter can be the transmitter itself (for example, a network device, a terminal device), or a component in the transmitter (for example, a processor, a chip, or a chip system, etc.), or a logic module or software that implements all or part of the transmitter function. The receiver can be the receiver itself (for example, a network device, a terminal device), or a component in the receiver (for example, a processor, a chip, or a chip system, etc.), or a logic module or software that implements all or part of the transmitter function. This application is not specifically limited here.

[0145] The method can be applied to 5G communication systems, 5.5G or future 6G communication systems. The method can also be applied to non-terrestrial communication systems, etc., which is not limited in this application. For example, the transmitter is a terminal device and the receiver is a network device; or, the transmitter is a network device and the receiver is a terminal device; or, the transmitter is a network device and the receiver is a network device; or, the transmitter is a terminal device and the receiver is a terminal device. It should be noted that Figure 11 is a schematic flow chart of an embodiment of the method of the present application, showing the detailed communication steps or operations of the method, but these steps or operations are only examples, and the embodiment of the present application can also perform other operations or variations of the various operations in Figure 11. In addition, the various steps in Figure 11 can be executed in a different order from that presented in Figure 11, and it is possible that not all operations in Figure 11 need to be executed. The method is performed as follows:

[0146] In step 1101, a transmitter obtains an OFDM signal. The OFDM signal is obtained by preprocessing a symbol sequence. The preprocessing includes: FDSS and a first process. The first process is used to spread the symbol sequence to obtain a spread sequence. The first process is performed before FDSS.

[0147] It should be noted that, in addition to the above-mentioned preprocessing, the symbol sequence also performs subcarrier mapping, IDFT and CP adding processing operations, etc. This application will not elaborate on them one by one here, and you can refer to the above-mentioned Figure 3 for understanding.

[0148] It should also be noted that preprocessing, in addition to FDSS and the first processing, also includes cyclic shifting of the symbol sequence, which is performed before the first processing. The cyclic shift of the symbol sequence by point c0 before the first processing can be understood by referring to the above formula 11 and is not further described here.

[0149] The first process can be understood as the bandwidth extension module in FIG10 above, which is used to introduce redundant sequences (hereinafter referred to as the first extended sequence and the second extended sequence). In an optional embodiment, the transmitter can extend the symbol sequence of length M based on the extension factor α to obtain an extended sequence of length (M+L). 0<α≤1, L and M are both positive integers, and L does not exceed M. For example, if the expansion factor is 0.5, then the extended sequence length is 1.5*M (1.5*M=M+0.5*M). In addition, if α*M is not an integer, rounding down, rounding up, or rounding up can be used to ensure that α*M is an integer. In another optional embodiment, the transmitter can extend a symbol sequence of length M based on the extension length L to obtain an extended sequence of length (M+L). For example, if the extension length is 6, then the extended sequence length is M+6.

[0150] Specifically, the expansion factor α may be determined based on at least one of the following:

[0151] The MCS corresponding to the OFDM signal, or the first factor θ; wherein the value of the first factor is related to the window function of the FDSS.

[0152] Among them, MCS includes modulation mode (for example, quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), etc. In this application, the modulation mode corresponding to the OFDM signal refers to the modulation mode of the symbol sequence) and the codec rate. When the number of subcarriers is determined, in one case, the larger α is, the smaller M is, that is, the less valid data the OFDM signal carries. Since the number of information bits = the number of coding bits * codec rate, and the number of coding bits = M*Q m , where Q m Indicates the number of bits carried by each valid data. For example, if the valid data is a QPSK symbol, then Q m =2; if the valid data is 16QAM symbol, then Q m =4. Based on this, it can be seen that, assuming the number of transmitted information bits and the modulation scheme remain unchanged, increasing α increases the code rate (i.e., α is negatively correlated with the codec rate), requiring a higher signal-to-noise ratio to achieve the same demodulation performance (e.g., BER). In another scenario, the smaller α, the larger M. In this case, the first processing operation introduces redundancy only to a small portion of the symbol sequence (i.e., the first and second extended sequences). The FDSS operation reduces the energy of the edge subcarriers, resulting in poor demodulation performance on the subcarriers without redundancy.

[0153] The value of the first factor is related to the FDSS window function. Different FDSS window functions ω(l) correspond to different values ​​of the first factor. The value of the first factor can be determined by referring to the following three methods:

[0154] Method 1: If ω1(l) is a Nyquist filter with a roll-off factor of β, then θ=β.

[0155] Method 2: If ω2(l) is a frequency-domain truncated Nyquist filter with a roll-off factor of β and a truncation factor of μ, then θ=β(1-μ).

[0156] Method 3: If ω3(l) is a non-Nyquist or non-frequency-domain truncated Nyquist filter, for example, its time-domain response is [0.28 1 0.28] (where 0.28, 1, and 0.28 are the three tap coefficients of the filter), a Nyquist filter or a frequency-domain truncated Nyquist filter with a shape similar to ω3(l) can be found to determine θ.

[0157] For example, a Nyquist filter with a roll-off factor of β has a frequency-domain response shape similar to ω3(l). In this case, θ = β + β0, where β0 is a decimal greater than or equal to zero and is specifically related to ω3(l). Alternatively, a frequency-domain truncated Nyquist filter with a roll-off factor of β and a truncation factor of μ has a frequency-domain response shape similar to ω3(l). In this case, θ = β(1-μ) + β0, where β0 is a decimal greater than or equal to zero and is specifically related to ω3(l). As shown in Figure 12, a frequency-domain truncated RRC filter with a roll-off factor of 1 and a truncation factor of 0.25 has a shape similar to ω3(l) with a time-domain response of [0.28 1 0.28] or [0.335 1 0.335]. Therefore, θ = 1*(1-0.25) + β0 = 0.75 + β0.

[0158] It should be noted that α≤θ can avoid degradation of signal demodulation performance. In addition, the length of the FDSS window function is the same as the length of the spread sequence.

[0159] Furthermore, the spreading factor α may also be related to the channel parameters between the transmitter and receiver. Channel parameters may include the channel time domain response, the channel frequency response, or the power delay profile. This correlation between the spreading factor α and channel parameters can be understood as meaning that different channels have different optimal α designs.

[0160] It should also be understood that the larger L1 and L2 are, the greater the frequency-selective channel gain that the OFDM signal can obtain. However, at this time, L or α is also larger, and the encoding and decoding bit rate is higher. In some channels, the increase in frequency-selective gain brought about by increasing α is not enough to offset the performance loss caused by the increase in bit rate.

[0161] Specifically, the above L may be determined based on at least one of the following: MCS, M, or the first factor θ corresponding to the OFDM signal.

[0162] Among them, MCS includes the modulation mode (for example, QPSK, QAM, etc., in this application, the modulation mode corresponding to the OFDM signal refers to the modulation mode of the symbol sequence) and the codec rate. When the number of subcarriers is determined, in one case, the larger L is, the smaller M is, that is, the number of valid data carried by the OFDM signal is smaller. Based on this, it can be seen that when the number of transmitted information bits and the modulation mode remain unchanged, increasing L will increase the code rate (that is, L is negatively correlated with the codec rate), resulting in a higher signal-to-noise ratio to achieve the same demodulation performance (such as BER). In another case, the smaller L is, the larger M is. At this time, the first processing operation only introduces redundancy to a small part of the elements in the symbol sequence. The FDSS operation reduces the energy of the edge subcarriers, resulting in poor data demodulation performance on subcarriers where no redundancy is introduced.

[0163] The first factor θ can be understood by referring to the above description and will not be described here. Based on this, we can see that the value of L is related to the length M and α of the symbol sequence. Since α≤θ, it can be inferred that the value of L is related to the first factor θ.

[0164] In one embodiment, the extended sequence may include a first extended sequence of length L1, a second extended sequence of length L2, and a symbol sequence of length M; wherein L1+L2=L; the first extended sequence is obtained by performing sequence processing on the first sequence in the symbol sequence (wherein the sequence processing may include: sequence replication, sequence conjugation, sequence reversal, etc.), and the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; the second extended sequence is obtained by performing sequence processing on the second sequence in the symbol sequence, and the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence. In the application, the first extended sequence and the second extended sequence can be considered as a method of adding redundancy to the symbol sequence. By introducing redundancy, the loss of OFDM signal communication demodulation performance caused by FDSS can be reduced / mitigated.

[0165] For example, the symbol sequence is [1 2 3 4 5 6 7 8 9 10], L1 is 3, L2 is 4, the first sequence is [1 2 3] (i.e., the subsequence corresponding to symbol sequence indices 0 to 2 (L1-1)), and the second sequence is [7 8 9 10] (i.e., the subsequence corresponding to symbol sequence indices 6 (M-L2) to 9 (M-1)). The first sequence is reversed to obtain a first extended sequence [3 2 1], and the second sequence is reversed to obtain a second extended sequence [10 9 8 7].

[0166] In addition, the length L1 of the first extended sequence may be equal to the length L2 of the second extended sequence. Based on the design that L1 is equal to L2, the frequency selectivity gain of the OFDM signal on the multipath channel can be maximized under a given L.

[0167] Optionally, the sequence processing method of the first processing includes one of the following:

[0168] Mode 1: A first extended sequence and a second extended sequence are obtained based on sequence replication, the first extended sequence is added to the end of the symbol sequence, and the second extended sequence is added to the head of the symbol sequence.

[0169] As shown in FIG13A , the symbol sequence S k , the length of the first sequence S1 in the symbol sequence is L1, the length of the second sequence S2 is L2, the first sequence is copied to obtain the first extended sequence S'1, and the second sequence is copied to obtain the second extended sequence S'2. Then the first extended sequence S'1 is added to the end of the symbol sequence, and the second extended sequence S'2 is added to the head of the symbol sequence to obtain the extended sequence For example, the symbol sequence is [1 2 3 4 5 6 7 8 9 10], L1 is 3, L2 is 3, the first sequence is [1 2 3] (i.e., the subsequence corresponding to symbol sequence indices 0 to 2 (L1-1)), and the second sequence is [8 9 10] (i.e., the subsequence corresponding to symbol sequence indices 7 (M-L2) to 9 (M-1)). After sequence replication, the first sequence is obtained as the first extended sequence [1 2 3], and after sequence replication, the second sequence is obtained as the second extended sequence [8 9 10]. The first extended sequence is added to the end of the symbol sequence, and the second extended sequence is added to the beginning of the symbol sequence to obtain the extended sequence [8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3].

[0170] Mode 2: A first extended sequence and a second extended sequence are obtained by taking conjugation of the sequence, the first extended sequence is added to the end of the symbol sequence, and the second extended sequence is added to the head of the symbol sequence.

[0171] As shown in FIG13B , the symbol sequence S k , the length of the first sequence S1 in the symbol sequence is L1, the length of the second sequence S2 is L2, the first sequence is copied to obtain the first extended sequence S'1, and the second sequence is copied to obtain the second extended sequence S'2. Then the first extended sequence S'1 is added to the end of the symbol sequence, and the second extended sequence S'2 is added to the head of the symbol sequence to obtain the extended sequence For example, the symbol sequence is [1+1j 2+1j 3+1j 4+1j 5+1j 6+1j 7+1j 8+1j 9+1j 10+1j], L1 is 3, L2 is 3, the first sequence is [1+1j 2+1j 3+1j] (i.e., the subsequence corresponding to symbol sequence indices 0 to 2 (L1-1)), and the second sequence is [8+1j 9+1j 10+1j] (i.e., the subsequence corresponding to symbol sequence indices 7 (M-L2) to 9 (M-1)). The first sequence is conjugated to obtain a first extended sequence, and the second sequence is conjugated to obtain a second extended sequence. The first spreading sequence is added to the end of the symbol sequence, and the second spreading sequence is added to the head of the symbol sequence to obtain the spreading sequence [8-1j 9-1j 10-1j 1+1j 2+1j 3+1j 4+1j 5+1j 6+1j 7+1j 8+1j 9+1j 10+1j 1-1j 2-1j 3-1j].

[0172] Mode 3: Obtain a first extended sequence and a second extended sequence based on sequence reversal, add the first extended sequence to the head of the symbol sequence, and add the second extended sequence to the tail of the symbol sequence.

[0173] As shown in FIG13C , the symbol sequence S k , the length of the first sequence S1 in the symbol sequence is L1, and the length of the second sequence S2 is L2. The first sequence is reversed to obtain the first extended sequence S′1, and the second sequence is reversed to obtain the second extended sequence S′2. The first extended sequence S′1 is then added to the head of the symbol sequence, and the second extended sequence S′2 is added to the tail of the symbol sequence. For example, the symbol sequence is [1 2 3 4 5 6 7 8 9 10], L1 is 3, L2 is 3, the first sequence is [1 2 3] (that is, the subsequence corresponding to the symbol sequence index 0 to 2 (L1-1)), and the second sequence is [8 9 10] (that is, the subsequence corresponding to the symbol sequence index 7 (M-L2) to 9 (M-1)). After the first sequence is reversed, the first extended sequence is [3 2 1], and after the second sequence is reversed, the second extended sequence is [10 9 8]. The first spreading sequence is added to the head of the symbol sequence, and the second spreading sequence is added to the tail of the symbol sequence to obtain the spreading sequence [3 2 1 1 2 3 4 5 6 7 8 9 10 10 9 8].

[0174] Mode 4: obtain a first extended sequence and a second extended sequence based on sequence reversal and sequence conjugation, add the first extended sequence to the head of the symbol sequence, and add the second extended sequence to the tail of the symbol sequence.

[0175] As shown in FIG13D , the symbol sequence Sk In the symbol sequence, the length of the first sequence S1 is L1, and the length of the second sequence S2 is L2. The first sequence is reversed and conjugated (in specific applications, the order of reversing and conjugating is not limited) to obtain the first extended sequence S′1, and the second sequence is reversed to obtain the second extended sequence S′2. The first extended sequence S′1 is then added to the head of the symbol sequence, and the second extended sequence S′2 is added to the tail of the symbol sequence. For example, if the symbol sequence is [1+1j 2+1j 3+1j 4+1j 5+1j 6+1j 7+1j 8+1j 9+1j 10+1j], L1 is 3, L2 is 3, the first sequence is [1 2 3] (i.e., the subsequence corresponding to symbol sequence indices 0 to 2 (L1-1)), and the second sequence is [8 9 10] (i.e., the subsequence corresponding to symbol sequence indices 7 (M-L2) to 9 (M-1)). The first sequence is reversed and conjugated to obtain the first extended sequence [3-1j 2-1j 1-1j]. The second sequence is reversed and conjugated to obtain the second extended sequence [10-1j 9-1j 8-1j]. The first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence to obtain the extended sequence [3-1j 2-1j 1-1j 1+1j 2+1j 3+1j 4+1j 5+1j 6+1j 7+1j 8+1j 9+1j 10+1j10-1j 9-1j 8-1j].

[0176] Methods 1 to 4 described above are merely exemplary. Other possible sequence processing methods are derived from the first processing method of Methods 1 to 4. For example, a first extended sequence is obtained by replicating the sequence, a second extended sequence is obtained by conjugating the sequence, and the first extended sequence is added to the end of the symbol sequence, while the second extended sequence is added to the beginning of the symbol sequence. Alternatively, a first extended sequence is obtained by conjugating the sequence, a second extended sequence is obtained by replicating the sequence, and the first extended sequence is added to the end of the symbol sequence, while the second extended sequence is added to the beginning of the symbol sequence. Alternatively, a first extended sequence is obtained by reversing the sequence, a second extended sequence is obtained by reversing the sequence and conjugating the sequence, and the first extended sequence is added to the beginning of the symbol sequence, while the second extended sequence is added to the end of the symbol sequence. Alternatively, a first extended sequence is obtained by reversing the sequence, a second extended sequence is obtained by reversing the sequence and conjugating the sequence, and the first extended sequence is added to the beginning of the symbol sequence, while the second extended sequence is added to the end of the symbol sequence. Alternatively, a first extended sequence is obtained by reversing the sequence and conjugating the sequence, and the second extended sequence is obtained by reversing the sequence, and the first extended sequence is added to the beginning of the symbol sequence, while the second extended sequence is added to the end of the symbol sequence. These are merely exemplary and not limiting. The shape of the FDSS window function resembles a mountain peak (see Figure 12 for details), i.e., the amplitude of the window function is high in the middle and low on both sides. In this application, by introducing a redundant design that matches the shape characteristics of the window function, namely, adding a first extended sequence to the tail or head of the symbol sequence, and adding a second extended sequence to the head or tail of the symbol sequence, the degradation of the two subsequences in the symbol sequence (i.e., the subsequence corresponding to index 0 to index L1-1 and the subsequence corresponding to index M-L2 to index M-1) caused by FDSS processing can be reduced, thereby improving the demodulation performance of OFDM signal communication.

[0177] In the present application, the transmitter and the receiver may pre-agree on the shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length of the symbol sequence M, L, the relative relationship between L and M, the expansion factor α and the sequence processing method of the first processing, and may also obtain the above information based on the notification message. For details, please refer to the description below.

[0178] If the transmitter is a terminal device and the receiver is a network device, before executing step 1101, the following steps are further executed:

[0179] In step 1100A, the transmitter obtains a first notification message from the receiver, where the first notification message is used to indicate at least one of the following parameters: the shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length of the symbol sequence M, L, the relative relationship between L and M, or the extension factor α. Specifically, the terminal device may receive the first notification message from a network device (in specific applications, the network device may be a receiver or other device, which is not specifically limited here), or the terminal device requests the network device for parameters for generating an OFDM signal, and the network device sends the first notification message to the terminal device, which is not specifically limited here in this application. The first notification message may be carried by downlink control information (DCI) or radio resource control signaling, which is only exemplified here and not specifically limited.

[0180] Among them, the first notification message indicates at least one parameter, which can be understood as the first notification message including the above parameters (for example, the length of the first extended sequence, etc.), and can also be understood as the first notification message indicating the above parameters through other parameters (character strings or encryption parameters, etc.) (for example, the first notification message includes C1, and the length of the first extended sequence is indicated by parameter C1, etc.).

[0181] In one embodiment, the first notification message includes the following types of parameters so that the transmitter generates the OFDM signal:

[0182] Type 1: cyclic shift amount, length of spread sequence (M+L), length of symbol sequence M, length of first spread sequence and / or length of second spread sequence.

[0183] Type 2: cyclic shift amount, length of symbol sequence, L, length of first spreading sequence, and / or length of second spreading sequence.

[0184] Type 3: cyclic shift amount, length of the spreading sequence (M+L), L, length of the first spreading sequence, and / or length of the second spreading sequence.

[0185] Type 4: cyclic shift amount, length of the spreading sequence (M+L), relative relationship between L and M, length of the first spreading sequence and / or length of the second spreading sequence.

[0186] Type 5. cyclic shift amount, length of the spreading sequence (M+L), spreading factor α, length of the first spreading sequence, and / or length of the second spreading sequence.

[0187] The above types are merely illustrative and do not specifically limit the types of parameters included in the first notification information. In addition, if the length of the first extended sequence is equal to the length of the second extended sequence, the first notification information may not indicate the length of the first extended sequence and / or the length of the second extended sequence to reduce signaling overhead.

[0188] If the transmitter and receiver have agreed in advance on the sequence processing method for the first processing, the transmitter may construct the OFDM signal with reference to the agreement and the first notification message. If the transmitter and receiver have not agreed in advance on the sequence processing method for the first processing, before executing the above step 1101, the transmitter also obtains a second notification message, which is used to indicate the sequence processing method for the first processing. The second notification message and the first notification message can be the same notification message or different notification messages, which is not specifically limited in this application. The second notification message can be carried via DCI or radio resource control signaling, which is only illustrative and not specifically limited.

[0189] In addition, if the transmitter is a network device and the receiver is a terminal device, the following steps can be performed:

[0190] In step 1100B, the transmitter outputs (or sends) a first notification message to the receiver. Step 1100B may also be performed after step 1102, and the execution order of the steps is not limited here.

[0191] It should be noted that the transmitter may send the first notification message and the second notification message so that the receiver can restore the extended sequence into a symbol sequence.

[0192] The receiver receives a first notification message. Based on the first notification message, the receiver can determine the length of the spreading sequence, the length of the symbol sequence, the length of the first spreading sequence, the length of the second spreading sequence, and the amount of cyclic shift, thereby determining how to demodulate the OFDM signal. Furthermore, the transmitter outputs a second notification message, which the receiver receives. Based on the second notification message, the receiver can determine the sequence processing method for the first processing to enable demodulation of the received OFDM signal. The receiver can perform different demodulation processes based on its own capabilities. For example, if the receiver's capabilities are limited, the receiver can only recover the symbol sequence based on the middle M data of the (M+L) received data. That is, the first L1 data (corresponding to the first spreading sequence) or the last L2 data (corresponding to the second spreading sequence) of the (M+L) received data are not used for symbol sequence recovery. If the receiver's capabilities are higher, the receiver can also use the first L1 data or the last L2 data of the (M+L) received data to achieve more accurate symbol sequence recovery.

[0193] In step 1102, the transmitter outputs (also referred to as transmits) an OFDM signal. Correspondingly, the receiver receives the OFDM signal.

[0194] Optionally, the transmitter also outputs FDSS parameters so that the receiver can recover the transmitted symbol sequence based on the received OFDM signal.

[0195] Step 1103: The receiver demodulates the OFDM signal to obtain a symbol sequence.

[0196] Specifically, the receiver obtains an estimate of the symbol sequence through analog-to-digital conversion, CP removal, serial-to-parallel conversion module, N-point DFT, subcarrier demapping, equalization (which simultaneously removes the effects of the channel and FDSS on the spread sequence. In addition, it is assumed that the equalizer outputs an M-length sequence in this step) and inverse processing of cyclic shift.

[0197] In this application, after the symbol sequence undergoes the first processing, an extended sequence is obtained, whose length is greater than the symbol sequence length. Therefore, after the first processing, redundancy (i.e., subsequences) is introduced into the symbol sequence. After the extended sequence undergoes FDSS processing, it undergoes subcarrier mapping and inverse Fourier transform to obtain an OFDM signal. Based on this OFDM signal, FDSS can improve the performance of target detection in ISAC scenarios. At the same time, the first processing can alleviate the performance loss of OFDM signal communication demodulation caused by FDSS.

[0198] In order to better illustrate the solution of this application, the following is a detailed description in conjunction with the above-mentioned Figures 14A and 14B. As shown in Figure 14A, the symbol sequence S k (obtained after a cyclic shift operation with a shift amount of c0), the length of the first sequence S1 in the symbol sequence is L1, the length of the second sequence S2 is L2, the first sequence is replicated to obtain the first extended sequence S'1, and the second sequence is replicated to obtain the second extended sequence S'2. Then, the first extended sequence S'1 is added to the end of the symbol sequence, and the second extended sequence S'2 is added to the head of the symbol sequence to obtain the extended sequence The extended sequence in FIG14A can be understood by referring to the following formula 12:

[0199] in, yes The lth element of is the extended sequence. N sc As shown in FIG14B , the symbol sequence S k , the length of the first sequence S1 in the symbol sequence is L1, the length of the second sequence S2 is L2, the first sequence is copied to obtain the first extended sequence S'1, and the second sequence is copied to obtain the second extended sequence S'2. Then the first extended sequence S'1 is added to the end of the symbol sequence, and the second extended sequence S'2 is added to the head of the symbol sequence to obtain the extended sequence The extended sequence in FIG14B can be understood by referring to the following formula 13:

[0200] in, It's S k conjugated sequence.

[0201] As FDSS input, after FDSS processing, we get As shown in the following formula 14:

[0202] Among them, ω T (l),l=0,1,…,N sc -1 represents the FDSS window function coefficient. T (l).

[0203] Through the first processing, for the k Each of the L1+L2 data at the head and tail is transmitted repeatedly using an additional subcarrier, which helps to improve the k Demodulation performance of the L1+L2 data at the head and tail.

[0204] The following introduces S k Assuming that the CP is sufficient, the received OFDM signal is subjected to CP removal, N-point DFT, and subcarrier demapping in sequence to obtain N sc Long frequency domain signal Y k (l),l=0,1,…,N sc -1. Assuming that the channel response on the lth subcarrier is C(l) and the noise is φ(l), then Y k (1) satisfies the following formula 15:

[0205] Where H(l)=C(l)ω T (l) represents the joint frequency domain response of FDSS and channel.

[0206] For S k (γ),γ=L1,…,M-L2-1These M-(L1+L2) data, combined with formula 15 and 12 or 13, can get formula 16: Y k (γ+L2)=H(γ+L2)S k (γ)+φ(γ+L2) Formula 16

[0207] Among them, S k(γ),γ=L1,…,M-L2-1 can be restored using zero forcing (ZF) equalization or minimum mean square error (MMSE) equalization. For example, when using ZF equalization, the following formula 17 is satisfied:

[0208] in, Indicates S k For example, when using MMSE equalization, the following formula 18 is satisfied:

[0209] in, represents the noise variance.

[0210] For S k There are two solutions to recover the L data (γ),γ∈{0,…,L1-1,M-L2,…,M-1}. The first is to rely only on Y k The first method uses L data (l), l∈{L2,L2+1,…,L2+L1-1,M,…,M+L2-1}; the second method uses, in addition to these L data, L data corresponding to the first and second spreading sequences. In the first scheme, one received data point is used to recover one transmitted data point. In the second scheme, two received data points are used to recover one transmitted data point. The second scheme has better performance than the first, but is more complex to implement. If the receiver capability is limited, the first recovery scheme can be selected; if the receiver capability is strong, the second scheme can be selected. The following describes these two schemes respectively.

[0211] The first method: using only Y k (L2+γ)Recovery S k (γ), where γ = 0,…, L1-1 or γ = M-L2,…, M-1.

[0212] Combining formula 15 with formula 12 or 13, we can get the following formula 19: k (L2+γ)=H(L2+γ)S k (γ)+φ(L2+γ) Formula 19

[0213] Since Formula 19 is the same as Formula 16, the ZF or MMSE equalization shown in Formula 17 or Formula 18 is used to obtain The detailed description is not provided here, and can be understood by referring to the above formula 17 or formula 18.

[0214] The second type:

[0215] For S kIf the L1 data (γ),γ=0,…,L1-1 are used in the manner shown in Formula 12 and combined with Formula 15, the following Formula 20 can be obtained:

[0216] S can be obtained based on formula 21 k Estimation of (γ) Where P(γ) is a vector with 1 row and 2 columns.

[0217] P(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, P(γ) satisfies the following formula 22:

[0218] in, The superscript H represents the Hermitian transpose. For example, according to the MMSE criterion, P(γ) satisfies the following formula 23:

[0219] For S k If we use the method shown in Formula 12 and combine it with Formula 15 for the L2 data (γ),γ=M-L2,…,M-1, we can get the following Formula 24:

[0220] S can be obtained based on formula 25 k Estimation of (γ) Among them, Q(γ) is a vector with 1 row and 2 columns.

[0221] Q(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, Q(γ) satisfies the following formula 26:

[0222] in, For example, according to the MMSE criterion, Q(γ) satisfies the following formula 27:

[0223] For S k If we use the method shown in Formula 13 and combine it with Formula 15 for the L1 data (κ),γ=0,…,L1-1, we can get the following Formula 28:

[0224] Based on formula 29, Where P(γ) is a vector with 1 row and 2 columns.

[0225] P(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, P(γ) satisfies the following formula 30:

[0226] in, The superscript H represents the Hermitian transpose. For example, according to the MMSE criterion, P(γ) satisfies the following formula 31:

[0227] For S k If we use the method shown in Formula 13 and combine it with Formula 15 for the L2 data (γ),γ=M-L2,…,M-1, we can get the following Formula 32:

[0228] Based on formula 33, Where Q(γ) is a vector with 1 row and 2 columns.

[0229] Q(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, Q(γ) satisfies the following formula 34:

[0230] in, For example, according to the MMSE criterion, Q(γ) satisfies the following formula 35:

[0231] In getting the estimated sequence After that, a cyclic shift of point -c0 is required to obtain an estimate of the original symbol sequence. This can be performed by referring to formula 36:

[0232] In order to better illustrate the solution of this application, the following is a detailed description in conjunction with the above-mentioned Figures 15A and 15B. As shown in Figure 15A, the symbol sequence S k , the length of the first sequence S1 in the symbol sequence is L1, the length of the second sequence S2 is L2, the first sequence is reversed to obtain the first extended sequence S'1, and the second sequence is reversed to obtain the second extended sequence S'2. Then the first extended sequence S'1 is added to the head of the symbol sequence, and the second extended sequence S'2 is added to the tail of the symbol sequence to obtain the extended sequence The extended sequence in FIG. 15A can be understood by referring to the following formula 37:

[0233] As shown in FIG15B , the symbol sequence S kIn the symbol sequence, the length of the first sequence S1 is L1, and the length of the second sequence S2 is L2. The first sequence is reversed and conjugated (in specific applications, the order of sequence reversal and sequence conjugation is not limited) to obtain the first extended sequence S'1, and the second sequence is reversed to obtain the second extended sequence S'2. Then, the first extended sequence S'1 is added to the head of the symbol sequence, and the second extended sequence S'2 is added to the tail of the symbol sequence to obtain the extended sequence The extended sequence in FIG15B can be understood by referring to the following formula 38:

[0234] in, yes The lth element of .

[0235] Through the first processing, for the k Each of the L1+L2 data at the head and tail is transmitted repeatedly using an additional subcarrier, which helps to improve the k Demodulation performance of the L1+L2 data at the head and tail.

[0236] The following introduces S k Assuming that the CP is sufficient, the received OFDM signal is subjected to CP removal, N-point DFT, and subcarrier demapping in sequence to obtain N sc Long frequency domain signal Y k (l),l=0,1,…,N sc -1. Assuming that the channel response on the lth subcarrier is C(l) and the noise is φ(l), then Y k (l) can be determined by formula 15.

[0237] For S k (γ),γ=L1,…,M-L2-1These M-(L1+L2) data, combined with formula 15, can be obtained as formula 39: Y k (γ+L1)=H(γ+L1)S k (γ)+φ(γ+L1) Formula 39

[0238] S k (γ),γ=L1,…,M-L2-1 can be restored using ZF equalization or MMSE equalization. For example, when using ZF equalization, the following formula 40 is satisfied:

[0239] in, Indicates S k For example, when using MMSE equalization, the following formula 41 is satisfied:

[0240] in, represents the noise variance.

[0241] For S k There are two solutions to recover the L data (γ),γ∈{0,…,L1-1,M-L2,…,M-1}. The first is to rely only on Y k The first method uses L data (l), l∈{L1,L1+1,…,2L1-1,M-L2+L1,…,M+L1-1}; the second method uses, in addition to these L data, L data corresponding to the first and second spreading sequences. In the first scheme, one received data is used to recover one transmitted data. In the second scheme, two received data are used to recover one transmitted data. The second scheme has better performance than the first, but is more complex to implement. If the receiver has limited capabilities, the first recovery scheme can be used; if the receiver has stronger capabilities, the second scheme can be used. The following describes these two schemes.

[0242] The first method: using only Y k (L1+γ)Recovery S k (γ), where γ = 0,…, L1-1 or γ = M-L2,…, M-1.

[0243] Combining formula 15 with formula 37 or 38, the following formula 42 can be obtained: k (L1+γ)=H(L1+γ)S k (γ)+φ(L1+γ) Formula 42

[0244] Since formula 42 is the same as formula 39, the ZF or MMSE equalization shown in formula 40 or formula 41 can be used to obtain The detailed description is not provided here and can be understood by referring to the above formula 40 or formula 41.

[0245] The second type:

[0246] For S k If the L1 data (γ),γ=0,…,L1-1 are used in the manner shown in Formula 37 and combined with Formula 15, the following Formula 43 can be obtained:

[0247] Based on formula 44, Where P(γ) is a vector with 1 row and 2 columns.

[0248] P(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, P(γ) satisfies the following formula 45:

[0249] in, The superscript H represents the Hermitian transpose. For example, according to the MMSE criterion, P(γ) satisfies the following formula 46:

[0250] For S k If we use the method shown in Formula 37 and combine it with Formula 15, we can get the following Formula 47:

[0251] Based on formula 48, Among them, Q(γ) is a vector with 1 row and 2 columns.

[0252] Q(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, Q(γ) satisfies the following formula 49:

[0253] in, For example, according to the MMSE criterion, Q(γ) satisfies the following formula 50:

[0254] For S k If the L1 data (γ),γ=0,…,L1-1 are used in the manner shown in Formula 38 and combined with Formula 15, the following Formula 51 can be obtained:

[0255] Based on formula 52, Where P(γ) is a vector with 1 row and 2 columns.

[0256] P(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, P(γ) satisfies the following formula 53:

[0257] in, The superscript H represents the Hermitian transpose. For example, according to the MMSE criterion, P(γ) satisfies the following formula 54:

[0258] For S k If the L2 data (γ),γ=M-L2,…,M-1 are used in the manner shown in Formula 38 and combined with Formula 54, the following Formula 55 can be obtained:

[0259] Based on formula 56, Where Q(γ) is a vector with 1 row and 2 columns.

[0260] Q(γ) can be designed according to the ZF criterion or the MMSE criterion. For example, when using the ZF criterion, Q(γ) satisfies the following formula 57:

[0261] in, For example, according to the MMSE criterion, Q(γ) satisfies the following formula 58:

[0262] In getting the estimated sequence After that, a cyclic shift of point -c0 is required to obtain an estimate of the original symbol sequence. This can be understood by referring to the above formula 36.

[0263] In order to better illustrate the improvement of the demodulation performance of OFDM signals with FDSS by the first processing in this application, the following simulation results are provided. T (l) is the RRC with a roll-off factor of 0.2 and a length of 720, i.e., N sc =720. S k is a QPSK symbol sequence. c0 = 0. The OFDM signal is transmitted over an AWGN channel. Figure 16 shows the demodulation BER performance with and without the first processing. The "conj" in the legend corresponding to the lower triangular curve indicates that the sequence processing operations of the first processing include sequence conjugation. Figure 16 shows that the first processing improves demodulation performance, while the sequence conjugation operation has no impact on performance.

[0264] Consider ω T (l) is the RRC with a roll-off factor of 0.5 and a length of 720. S k is a QPSK symbol sequence, c0 = 0. Consider a static tapped delay line (TDL)-B channel with a delay of 600 ns. Considering ideal channel estimation, low-density parity-check code is used for channel coding. The code rate (CR) of the scheme without bandwidth extension (as the baseline) is 1 / 3. Under the condition of communication capacity alignment (or under the condition of alignment of the number of transmitted information bits), the code rate of the scheme with bandwidth extension is The maximum value of α is 0.5 (since α≤θθ=0.5). Therefore, if α=0.5, the encoding and decoding rate is increased from 1 / 3 to 0.5. Figure 17A shows the demodulation block error rate (BLER) of the first processing scheme under different α values ​​and different L values. Based on FIG17A , it can be seen that when the L value is appropriate, the demodulation performance is best. Based on FIG17A , it can be seen that when L=136 and CR=0.41, the demodulation performance is best, and when L=240 and CR=0.5, the demodulation performance is worst.

[0265] In FIG17B , except that the baseline code rate is changed to 2 / 3, other parameters are the same as those in FIG17A . FIG17B shows the demodulated BLER of the first processing scheme under different α values ​​corresponding to different L values.

[0266] Based on Figures 17A and 17B , it can be seen that for some values ​​of α, the performance of the first processing scheme is inferior to that of the baseline scheme (i.e., the scheme without the first processing). For example, when α = θ, due to the significant increase in code rate, the improvement in demodulation SNR caused by the code rate increase exceeds the decrease in demodulation SNR caused by the first processing. For another example, when α = 0, although the code rate is the lowest, the data demodulation performance on the subcarriers with reduced energy by FDSS but no redundancy is poor. Based on this, it can be seen that the optimal α is between 0 and θ.

[0267] Figure 17C shows the demodulation BLER at different shift amounts c0 when the signal-to-noise ratio is -3.1dB and -3.2dB. The horizontal axis is the shift amount, and the vertical axis is the BLER. L = 136, and other parameters are the same as Figure 17A. Figure 17D shows the demodulation BLER at different shift amounts when the signal-to-noise ratio is 2.5dB and 2.6dB. L = 86, and other parameters are the same as Figure 17B. It can be seen that different shift amounts have different BLER performance. For example, from Figure 17C, it can be seen that c0 = 184 has better BLER performance than c0 = 0. The reason for this phenomenon is that the M coded symbols in the M-length symbol sequence have different anti-interference capabilities. Therefore, the OFDM demodulation performance can be improved by selecting an appropriate c0.

[0268] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of device interaction. It is understandable that, in order to implement the above functions, each device may include a hardware structure and / or software module that performs each function. Those skilled in the art should easily appreciate that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven hardware manner depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0269] In the embodiments of the present application, the functional units of the device can be divided according to the above method examples. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or software functional units.

[0270] In the case of adopting an integrated unit, Figure 18 shows a possible exemplary block diagram of the communication device involved in the embodiments of the present application. As shown in Figure 18, the communication device 1800 may include: a processing unit 1801 and a transceiver unit 1802. The processing unit 1801 is used to control and manage the actions of the communication device 1800. The transceiver unit 1802 is used to support communication between the communication device 1800 and other devices. Optionally, the transceiver unit 1802 may include a receiving unit and / or a sending unit, which are used to perform receiving and sending operations respectively. Optionally, the communication device 1800 may also include a storage unit for storing program code and / or data of the communication device 1800. The transceiver unit may be referred to as an input / output unit, a communication unit, etc., and the transceiver unit may be a transceiver; the processing unit may be a processor. When the communication device is a module (such as a chip) in a communication device, the transceiver unit may be an input / output interface, an input / output circuit, or an input / output pin, etc., and may also be referred to as an interface, a communication interface, or an interface circuit, etc.; the processing unit may be a processor, a processing circuit, or a logic circuit, etc. Specifically, the communication device may be the above-mentioned transmitter, receiver, etc.

[0271] In one embodiment, when the communication device 1800 is a transmitter, the processing unit 1801 is used to obtain an OFDM signal, which is obtained by preprocessing the symbol sequence. The preprocessing includes: frequency domain spectrum shaping FDSS and a first processing. The first processing is used to extend the symbol sequence to obtain an extended sequence. The first processing is performed before FDSS; the transceiver unit 1802 is used to output the OFDM signal.

[0272] In another embodiment, the communication device 1800 is a receiver, and the transceiver unit 1802 is used to receive an OFDM signal. The OFDM signal is obtained by preprocessing the symbol sequence. The preprocessing includes: frequency domain spectrum shaping FDSS and a first processing. The first processing is used to extend the symbol sequence to obtain an extended sequence. The first processing is performed before FDSS; the processing unit 1801 is used to demodulate the OFDM signal to obtain a symbol sequence.

[0273] In an optional manner, the pre-processing further includes: performing a cyclic shift on the symbol sequence, and the cyclic shift is performed before the first processing.

[0274] In an optional manner, the first process is used to spread the symbol sequence to obtain the spread sequence, including: spreading the symbol sequence with a length of M based on a spreading factor α to obtain a spread sequence with a length of (M+L),

[0275] In an optional manner, α is determined based on at least one of the following:

[0276] The MCS corresponding to the OFDM signal, or the first factor θ; wherein the value of the first factor is related to the window function of the FDSS.

[0277] In an optional manner, the first processing is used to extend the symbol sequence to obtain an extended sequence, including: extending the symbol sequence of length M based on the extension length L to obtain an extended sequence of length (M+L), where M and L are both positive integers, and L does not exceed M.

[0278] In an optional manner, L is determined based on at least one of the following:

[0279] The MCS, M, or the first factor θ corresponding to the OFDM signal; wherein the value of the first factor is related to the window function of the FDSS.

[0280] In an optional manner, the extended sequence includes a first extended sequence with a length of L1 and a second extended sequence with a length of L2; wherein the first extended sequence is obtained by performing sequence processing on the first sequence in the symbol sequence, and the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; and the second extended sequence is obtained by performing sequence processing on the second sequence in the symbol sequence, and the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence.

[0281] In an optional embodiment, L1 is equal to L2.

[0282] In an optional manner, the sequence processing of the first processing includes one of the following:

[0283] Obtaining a first extended sequence and a second extended sequence based on sequence replication, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the head of the symbol sequence; or,

[0284] Taking conjugation of the sequence to obtain a first extended sequence and a second extended sequence, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the beginning of the symbol sequence; or,

[0285] Obtaining a first extended sequence and a second extended sequence based on sequence reversal, adding the first extended sequence to the head of the symbol sequence, and adding the second extended sequence to the tail of the symbol sequence; or,

[0286] A first extended sequence and a second extended sequence are obtained based on sequence reversal and sequence conjugation, the first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence.

[0287] In an optional manner, the transceiver unit 1802 also obtains or sends a first notification message, where the first notification message is used to indicate at least one of the following parameters: the shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length of the symbol sequence M, L, the relative relationship between L and M, or the extension factor α.

[0288] In an optional manner, the transceiver unit 1802 further obtains or sends a second notification message, where the second notification message is used to indicate a sequence processing method of the first processing.

[0289] In addition, Figure 19 shows a simplified schematic diagram of the structure of a terminal device provided by this application. For ease of understanding and illustration, Figure 19 uses a mobile phone as an example of a terminal. As shown in Figure 19, the terminal includes a processor, memory, radio frequency circuit, antenna, and input and output devices.

[0290] The processor is mainly used to process communication protocols and communication data, as well as control terminal devices, execute software programs, process software program data, etc.

[0291] Memory is mainly used to store software programs and data.

[0292] Radio frequency circuits are mainly used for conversion between baseband signals and radio frequency signals and for processing radio frequency signals.

[0293] Antennas are mainly used to send and receive radio frequency signals in the form of electromagnetic waves.

[0294] Input and output devices, such as touch screens, display screens, keyboards, etc., are mainly used to receive data input by users and output data to users.

[0295] It should be noted that some types of terminal devices may not have input and output devices.

[0296] When data needs to be sent, the processor performs baseband processing on the data to be transmitted and outputs the baseband signal to the RF circuit. The RF circuit then performs RF processing on the baseband signal and transmits it via the antenna in the form of electromagnetic waves. When data is sent to a terminal device, the RF circuit receives the RF signal via the antenna, converts it into a baseband signal, and outputs the baseband signal to the processor, which converts the baseband signal into data and processes it.

[0297] For ease of explanation, Figure 19 shows only one memory and processor. In actual terminal device products, one or more processors and one or more memories may exist. Memory may also be referred to as a storage medium or storage device. The memory may be provided independently of the processor or integrated with the processor, and this is not limited in this embodiment of the present application.

[0298] In the embodiment of the present application, the antenna and radio frequency circuit with transceiver functions can be regarded as the transceiver unit of the terminal device, and the processor with processing function can be regarded as the processing unit of the terminal device.

[0299] As shown in Figure 19, terminal 1900 includes a transceiver unit 1910 and a processing unit 1920. Transceiver unit 1910 may also be called a transceiver, transceiver, transceiver device, etc. Processing unit 1920 may also be called a processor, processing board, processing module, processing device, etc.

[0300] Alternatively, the device in the transceiver unit 1910 that implements the receiving function may be considered a receiving unit, and the device in the transceiver unit 1910 that implements the transmitting function may be considered a transmitting unit. That is, the transceiver unit 1910 includes a receiving unit and a transmitting unit. The transceiver unit may also be sometimes referred to as a transceiver, a transceiver, or a transceiver circuit. The receiving unit may also be sometimes referred to as a receiver, a receiver, or a receiving circuit. The transmitting unit may also be sometimes referred to as a transmitter, a transmitter, or a transmitting circuit.

[0301] It should be understood that the transceiver unit 1910 is used to perform the sending and receiving operations of the terminal device in the above method embodiment, and the processing unit 1920 is used to perform other operations except the sending and receiving operations on the terminal device in the above method embodiment.

[0302] When the terminal device is a chip, the chip includes a transceiver unit and a processing unit (processor). The transceiver unit can be an input / output circuit or a communication interface, such as an IO interface; the processing unit is a processor, microprocessor, integrated circuit, or logic circuit integrated on the chip. The transceiver unit, processing unit, and memory can be integrated into a first chip, such as a modem or a system-on-chip (SoC). The radio frequency circuit can be located in a second chip, such as a radio frequency front-end (RFF).

[0303] This application also provides a network device. Figure 20 shows a schematic diagram of the structure of a network device 2000 provided in an embodiment of this application. This network device 2000 can be applied to the system shown in Figure 1. For example, network device 2000 can be a network device in the system shown in Figure 1, configured to perform the functions of the network device in the above-described method embodiment. It should be understood that the following is merely an example, and in future communication systems, network devices may have other forms and configurations.

[0304] For example, in a 5G communication system, the network device 2000 may include a CU, a DU, and an AAU. Compared to the network device in an LTE communication system, which consists of one or more radio frequency units, such as a remote radio unit (RRU) and one or more building base band units (BBU):

[0305] The non-real-time portion of the original BBU will be separated and redefined as a CU, responsible for handling non-real-time protocols and services. Some of the BBU's physical layer processing functions will be merged with the original RRU and passive antennas into the AAU. The remaining BBU functions will be redefined as a DU, responsible for handling physical layer protocols and real-time services. In short, the CU and DU are differentiated by the real-time nature of their processing, and the AAU is a combination of the RRU and antenna.

[0306] The CU, DU, and AAU can be deployed separately or together, resulting in a variety of network deployment configurations. One possible deployment configuration, shown in Figure 20, is consistent with traditional 4G network equipment, with the CU and DU deployed on shared hardware. It should be understood that Figure 20 is merely an example and does not limit the scope of protection of this application. For example, the deployment configuration may also include the DU being deployed in the BBU room, the CU being deployed centrally, or the DU being deployed centrally, with the CU being centralized at a higher level.

[0307] The AAU 2100 can implement transceiver functions and correspond to the transceiver unit 1802 in FIG. 18 . Optionally, the AAU 2100 can also be referred to as a transceiver, a transceiver circuit, or a transceiver, and may include at least one antenna 2101 and a radio frequency unit 2102. Optionally, the AAU 2100 may include a receiving unit and a transmitting unit. The receiving unit may correspond to a receiver (or receiver, receiving circuit), and the transmitting unit may correspond to a transmitter (or transmitter, transmitting circuit). The CU and DU 2200 can implement internal processing functions and correspond to the processing unit 1801 in FIG. 18 . Optionally, the CU and DU 2200 can control network devices and may be referred to as controllers. The AAU, CU, and DU may be physically co-located or physically separated.

[0308] In addition, the network equipment is not limited to the form shown in Figure 20, but can also be other forms: for example: including a BBU and an adaptive radio unit (ARU), or including a BBU and an AAU; it can also be customer premises equipment (CPE), or it can be other forms, which are not limited in this application.

[0309] In one example, the CU and DU2200 may be composed of one or more single boards, and multiple single boards may jointly support a wireless access network with a single access standard (such as an LTE network), or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, a future network or other networks). The CU and DU2200 also include a memory 2201 and a processor 2202. The memory 2201 is used to store necessary instructions and data. The processor 2202 is used to control the network device to perform necessary actions, such as controlling the network device to execute the operation process of the network device in the above method embodiment. The memory 2201 and the processor 2202 can serve one or more single boards. That is, a memory and a processor can be set separately on each single board. Alternatively, multiple single boards may share the same memory and processor. In addition, necessary circuits may be set on each single board.

[0310] It should be understood that the network device 2000 shown in Figure 20 is capable of implementing the network device functions involved in the method embodiment of Figure 11. The operations and / or functions of the various units in the network device 2000 are respectively for implementing the corresponding processes performed by the network device in the method embodiment of the present application. To avoid repetition, detailed descriptions are appropriately omitted here. The structure of the network device illustrated in Figure 20 is only one possible form and should not constitute any limitation on the embodiments of the present application. The present application does not exclude the possibility of other forms of network device structures that may appear in the future.

[0311] The CU and DU 2200 can be used to perform the actions implemented within the network device described in the previous method embodiments, while the AAU 2100 can be used to perform the actions described in the previous method embodiments in which the network device sends or receives data to or from the terminal device. For details, please refer to the description in the previous method embodiments and will not be repeated here.

[0312] The present application also provides a communication system including a terminal device and a network device. The terminal device is configured to execute all or part of the steps executed by the terminal device in the embodiment shown in FIG. 11 . The network device is configured to execute all or part of the steps executed by the network device in the embodiment shown in FIG. 11 .

[0313] Based on the above embodiments, embodiments of the present application further provide a computer-readable storage medium, which stores instructions that, when executed, implement the method of any of the above embodiments. The computer-readable storage medium can be either a volatile storage medium or a non-volatile storage medium. The computer-readable storage medium can include various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk.

[0314] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, compact disc read-only memory (CD-ROM), optical storage, etc.) containing computer-usable program code.

[0315] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0316] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0317] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

Claims

1. A communication method, characterized in that: include: Acquire an orthogonal frequency division multiplexing (OFDM) signal, where the OFDM signal is obtained by preprocessing a symbol sequence, where the preprocessing includes frequency domain spectrum shaping (FDSS) and a first process, where the first process extends the symbol sequence to obtain an extended sequence, the first process being performed before the FDSS; Output the OFDM signal.

2. The method according to claim 1, characterized in that The pre-processing further includes: performing a cyclic shift on the symbol sequence, wherein the cyclic shift is performed before the first processing.

3. The method according to claim 1 or 2, characterized in that The first processing extends the symbol sequence to obtain an extended sequence, comprising: extending the symbol sequence of length M based on an extension factor α to obtain an extended sequence of length (M+L); 4. The method according to claim 3, characterized in that The α is determined based on at least one of the following: A modulation and coding scheme MCS corresponding to the OFDM signal, or a first factor θ; The value of the first factor is related to the window function of the FDSS.

5. The method according to any one of claims 1 to 4, characterized in that: The first process extends the symbol sequence to obtain an extended sequence, including: extending the symbol sequence with a length of M based on an extension length L to obtain an extended sequence with a length of (M+L).

6. The method according to any one of claims 3 to 5, characterized in that: The L is determined based on at least one of the following: The modulation and coding scheme MCS corresponding to the OFDM signal, the M, or the first factor θ; The value of the first factor is related to the window function of the FDSS.

7. The method according to any one of claims 1 to 6, characterized in that: The extended sequence includes a first extended sequence with a length of L1, a second extended sequence with a length of L2 and the symbol sequence with a length of M; The first extended sequence is obtained by performing sequence processing on a first sequence in the symbol sequence, where the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; the second extended sequence is obtained by performing sequence processing on a second sequence in the symbol sequence, where the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence.

8. The method according to claim 7, characterized in that The L1 is equal to the L2.

9. The method according to claim 7 or 8, characterized in that The sequence processing method of the first processing includes one of the following: Obtaining the first extended sequence and the second extended sequence based on sequence replication, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the head of the symbol sequence; or, The first extended sequence and the second extended sequence are obtained based on sequence conjugation, the first extended sequence is added to the end of the symbol sequence, and the second extended sequence is added to the head of the symbol sequence; or, Obtain the first extended sequence and the second extended sequence based on sequence reversal, add the first extended sequence to the head of the symbol sequence, and add the second extended sequence to the tail of the symbol sequence; or, The first extended sequence and the second extended sequence are obtained based on sequence reversal and sequence conjugation, the first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence.

10. The method according to any one of claims 7 to 9, characterized in that: Also includes: Obtain or output a first notification message, where the first notification message is used to indicate at least one of the following parameters: The shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length M of the symbol sequence, the L, the relative relationship between the L and the M, or the extension factor α.

11. The method according to claim 10, characterized in that Also includes: A second notification message is obtained or output, where the second notification message is used to indicate a sequence processing method of the first processing.

12. A communication method, characterized in that: include: receiving an orthogonal frequency division multiplexing (OFDM) signal, the OFDM signal being obtained by preprocessing a symbol sequence, the preprocessing comprising: frequency domain spectrum shaping (FDSS) and a first process, the first process extending the symbol sequence to obtain an extended sequence, the first process being performed before the FDSS; The OFDM signal is demodulated to obtain the symbol sequence.

13. The method according to claim 12, characterized in that The pre-processing further includes: performing a cyclic shift on the symbol sequence, wherein the cyclic shift is performed before the first processing.

14. The method according to claim 12 or 13, characterized in that The first processing extends the symbol sequence to obtain an extended sequence, comprising: extending the symbol sequence of length M based on an extension factor α to obtain an extended sequence of length (M+L); 15. The method according to claim 14, characterized in that The α is determined based on at least one of the following: A modulation and coding scheme MCS corresponding to the OFDM signal, or a first factor θ; The value of the first factor is related to the window function of the FDSS.

16. The method according to any one of claims 12 to 15, characterized in that: The first process extends the symbol sequence to obtain an extended sequence, including: extending the symbol sequence with a length of M based on an extension length L to obtain an extended sequence with a length of (M+L).

17. The method according to any one of claims 14 to 16, characterized in that: The L is determined based on at least one of the following: The modulation and coding scheme MCS corresponding to the OFDM signal, the M, or the first factor θ; The value of the first factor is related to the window function of the FDSS.

18. The method according to any one of claims 12 to 17, characterized in that: The extended sequence includes a first extended sequence with a length of L1, a second extended sequence with a length of L2 and the symbol sequence with a length of M; The first extended sequence is obtained by performing sequence processing on a first sequence in the symbol sequence, where the first sequence is a subsequence corresponding to index 0 to index L1-1 in the symbol sequence; the second extended sequence is obtained by performing sequence processing on a second sequence in the symbol sequence, where the second sequence is a subsequence corresponding to index M-L2 to index M-1 in the symbol sequence.

19. The method according to claim 18, characterized in that The L1 is equal to the L2.

20. The method according to claim 18 or 19, characterized in that The sequence processing method of the first processing includes one of the following: Obtaining the first extended sequence and the second extended sequence based on sequence replication, adding the first extended sequence to the end of the symbol sequence, and adding the second extended sequence to the head of the symbol sequence; or, The first extended sequence and the second extended sequence are obtained based on sequence conjugation, the first extended sequence is added to the end of the symbol sequence, and the second extended sequence is added to the head of the symbol sequence; or, Obtain the first extended sequence and the second extended sequence based on sequence reversal, add the first extended sequence to the head of the symbol sequence, and add the second extended sequence to the tail of the symbol sequence; or, The first extended sequence and the second extended sequence are obtained based on sequence reversal and sequence conjugation, the first extended sequence is added to the head of the symbol sequence, and the second extended sequence is added to the tail of the symbol sequence.

21. The method according to any one of claims 18 to 20, characterized in that: Also includes: Obtain or output a first notification message, where the first notification message is used to indicate at least one of the following parameters: The shift amount of the cyclic shift, the length of the first extended sequence, the length of the second extended sequence, the length of the extended sequence (M+L), the length M of the symbol sequence, the L, the relative relationship between the L and the M, or the extension factor α.

22. The method according to claim 21, characterized in that Also includes: A second notification message is obtained or output, where the second notification message is used to indicate a sequence processing method of the first processing.

23. A communication device, characterized in that: include: at least one processor and memory; The memory is used to store computer programs or data; The at least one processor is configured to execute part or all of the computer program or data so that the method according to any one of claims 1 to 22 is executed.

24. A computer-readable storage medium, characterized in that The computer-readable storage medium stores instructions, and when the instructions are executed by a computer, the method according to any one of claims 1 to 22 is performed.

25. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is run on a computer, the method according to any one of claims 1 to 22 is performed.

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